Of various types of sensors using a semiconductor such as a gas sensor, a humidity sensor, and a temperature sensor, there are some sensors which require a relatively long time period from a start of measurement until a value of the output signal (for example, a voltage value) is converged. That is, when a certain property of an object to be measured is evaluated on the basis of an output signal from a sensor, it is not possible to evaluate the property until a value of the output signal is converged. For example, a semiconductor gas sensor for detecting a smell requires about 600 seconds, for example, from a start of measurement until the value of the output signal is converged.
Note that as used herein, “the value of the output signal is converged” means that a difference between a value of the output signal at a certain time after a sufficient time period elapses and a value of the output signal at a time before the certain time, is a value, during a prescribed time period, within a prescribed range, and the converged value of the output signal is referred to as “converged value”. Further, a time period from a start of measurement until the value of the output signal is converged is referred to as “response time period”, and a period until the response time period elapses is referred to as “transition response period”.
In order to quickly evaluate a certain property of an object to be measured on the basis of the output signal from the sensor, the converged value corresponding to the property may be estimated on the basis of the value of the output signal in the transition response period. Various methods of estimating such a converged value are studied. For example, PTL 1 discloses a method of estimating what performance a machine having different performance depending on each driving operation environment demonstrates under an unknown operation environment, for example. According to the estimation method described in PTL 1, input operation environment data is categorized according to a categorization condition, the categorized data is supplied to a corresponding single model, and an estimated value is evaluated from the single model.